5-phenyl-3-thioureido-1,2,4-thiadiazole (PTT) is used in the preparation of agricultural fungicides. Kurzer (J. Chem. Soc., Perkin Trans. (1985), 1(2), 311-314) discloses the synthesis of PTT from 3-[N'-(benzoyl)thioureido]-5-phenyl-1,2,4-thiadiazole (BzPTT). The conversion is effected by treating the BzPTT with a boiling 3 M aqueous solution of NaOH for 6-8 minutes, followed by acidification of the reaction milieu with concentrated hydrochloric acid, and then basification with gaseous ammonia. The PTT is recrystallized in a solution of acetone/ethanol (1:1 v/v) (300 mL/g) or nitrobenzcne (5 ml/g) to provide an overall 85% yield recovery, on a 10.2 g-scale reaction.
Kurzer (J. Heterocycl. Chem., (1989), 26, 355) discloses the synthesis of 5-Phenyl-3-thioureido-1,2,4-thiadiazole (PTT) from 1-ethoxycarbonyl-3,5-(3'-phenyl-1',2',4'-thiadiazol-3'-yl) thiourea (EtPTT). EtPTT is converted to PTT by suspending the EtPTT in a boiling solution of ethanol and NaOH (3 M) with reflux for 1 hour, acidifying the reaction milieu with 3 M hydrochloric acid, and recrystallizing the PTT from dimethylformamide (DMF). The PTT was isolated in 72% yield, on a 1.54 g-scale reaction.